Model parameters of RSFs for habitat selection.

<p>Model parameters of RSFs for habitat selection.</p

Common Starlings (<i>Sturnus vulgaris</i>) increasingly select for grazed areas with increasing distance-to-nest

<div><p>The abundant and widespread Common Starling (<i>Sturnus vulgaris</i>) is currently declining across much of Europe due to landscape changes caused by agricultural intensification. The proximate mechanisms causing adverse effects to breeding Starlings are unclear, hampering our ability to implement cost-efficient agri-environmental schemes to restore populations to former levels. This study aimed to show how this central foraging farmland bird uses and selects land cover types in general and how use of foraging habitat changes in relation to distance from the nest. We attached GPS-loggers to 17 breeding Starlings at a Danish dairy cattle farm in 2015 and 2016 and analysed their use of different land cover types as a function of distance intervals from the nest and their relative availability. As expected for a central place forager, Starlings increasingly avoided potential foraging areas with greater distance-to-nest: areas ≥ 500 m were selected > 100 times less frequently than areas within 100 m. On average, Starlings selected the land cover category Grazed most frequently, followed by Short Grass, Bare Ground, Meadow and Winter Crops. Starlings compensated for elevated travel costs by showing increasing habitat selection the further they foraged from the nest. Our results highlight the importance of Grazed foraging habitats close to the nest site of breeding Starlings. The ecological capacity of intensively managed farmlands for insectivorous birds like the Starling is decreasing through conversion of the most strongly selected land cover type (Grazed) to the least selected (Winter Crops) which may be further exacerbated through spatial segregation of foraging and breeding habitats.</p></div

Positional fixes from two different foraging breeding Starlings (<i>Sturnus vulgaris</i>).

<p>The map shows positions of two different birds (left: S7, 2015 in a) and right: S9a, 2016 in b)) recorded using GPS loggers at a dairy farm in Hjortkær, Jutland, Denmark overlaid on the ringing and nest site (central blue diamond) and the surrounding fields indicating the different crops and the foraging positions of one Starling during c. 24 hours. The categories Building, Garden and Forest are only shown for clarity and were not included in the analysis. The large black circle represents the limit of habitat classification and has a radius of 1000 m (See also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0182504#pone.0182504.s003" target="_blank">S1 Table</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0182504#pone.0182504.s001" target="_blank">S1 Fig</a> in Supplementary Materials for the full set of all mapped individuals).</p

Foraging distance for breeding Starlings.

<p>(A) Proportion of GPS-locations of 17 foraging Starlings at different distance intervals from the nest, the different symbols indicate different birds. (B) Selection coefficients of distance intervals relative to the selection in the nearest interval (0–99 m) from RSF that also accounts for selection of land cover types. The anti-log of the coefficients indicate the approximate odds ratio by which a distance category is used relative to availability compared to 0–99 m from the nest (horizontal stippled lines indicate odds ratios of 1:10 and 1:100 as a guide).</p

Selection of land cover types.

<p>Selection of land cover types.</p

Schlaich_etal_2017_BiolLetters_ high_resolution_data_20170410

This file contains the high resolution GPS-tracking data of Montagu’s Harriers used to calculate correction factors according to sampling interval and contains the following columns: season (name of the bird, years), date_time (date and time in UTC), ann.rough (annotation of annual cycle phases: breeding, autumn migration, winter, spring migration), latitude, longitude, speed_2d (instantaneous speed measured by the GPS-device)